Skin is the largest organ of the human body, representing approximately 16% of a person's total body weight. Because it interfaces with the environment, skin has an important function in body defense, acting as an anatomical barrier from pathogens and other environmental substances. Skin also provides a semi-permeable barrier that prevents excessive fluid loss while ensuring that essential nutrients are not washed out of the body. Other functions of skin include insulation, temperature regulation, and sensation. Skin tissue may be subject to many forms of damage, including burns, trauma, disease, and depigmentation (e.g., vitiligo).
Skin grafts are often used to repair such skin damage. Skin grafting is a surgical procedure in which a section of skin is removed from one area of a person's body (autograft), removed from another human source (allograft), or removed from another animal (xenograft), and transplanted to a recipient site of a patient, such as a wound site. Typically it is preferable to use an autograft instead of an allograft or a xenograft to reduce complications, such as graft failure and rejection of the skin graft.
A problem encountered when using an autograft is that skin is taken from another area of a person's body to produce the graft, resulting in trauma and wound generation at the donor site. Generally, the size of the graft matches the size of the recipient site, and thus a large recipient site requires removal of a large section of skin from a donor site, leading to increased pain and discomfort and longer healing time. Additionally, as the size of the section of skin removed from the donor site increases, so does the possibility of infection.
Techniques have been developed for harvesting a large number of smaller grafts, e.g., so-called micrografts, to reduce the trauma at the donor site. By removing only a fraction of the skin at a donor site and leaving regions of healthy skin surrounding the excised regions, a large amount of skin for transplantation can be obtained with less discomfort. Micrograft harvesting can also reduce the healing time and risk of infection at the donor site.
However, micrografts are often difficult to obtain due to the tendency of small skin excisions to curl or fold over onto themselves or the surgical instrument (e.g., dermatome), making them unsuitable for use. This folding/curling tendency is particularly problematic the thinner the layer is that is being obtained, such as the epidermal layer. To some extent, suction blistering can reduce this problem by raising a plurality of skin blisters that can be more readily captured (e.g., by an adhesive substrate) and maintained in a planar orientation until transplanted. Suction blistering typically involves both a source of negative pressure and a heat source to warm the skin which facilitates blister formation. However, current suction blistering methods and devices can sometimes be time-consuming, typically requiring 30 minutes or more to form harvestable grafts.